Dear Durgaputra,
Thank you for your answers, I am looking for representations of Tara to find out. Actually I thought it was Kali for a long time but now that you said it, I am pretty sure that it is not her.
So it is a woman for sure or a goddess, with a trident and a necklace made of skull heads. Two arms though ..
Thank you for your answer, i would welcome any other comment